Roof treatment required for heat insulation

You would be best to add a second roof with an air gap of 120mm 4" the second roof can be made of metal and painted silver. This will allow a continual flow of air between the two layers taking the heat away the reflective paint will help to reduce the solar radiation. If you can fit solar collectors you can have free hot water as well.

When it gets colder in the winter you will have a better protection as well.

If wind is a serious threat make sure that you secure everything really well.

Put internal foam panels 4" thick on all ceilings and cover with fireproof board (gyproc). This is the cheapest method and 2 men can do it easily. Fiberglass also works, but the attachment if not so easy and the insulation is not as good.

Much more expensive is to cover the roof with 4" foam, and a hardboard layer with attachment to the RCC and over that place a rubber membrane roof.

Both these methods will save a lot of money on air conditioning.

To be thourough, do all the walls as well. Inside is cheaper and adds about 5" to each wall.

Why waste time and money on foams.Air is free.Use just the air gap for roof. Hot air will stick to bottom of upper skin. Coldest on top of lower skin.And the heat transfer will just be CONDUCTION THROUGH AIR--miniscule. Vertical walls are not easy.Because-- hottest air will try to reach up and cause circulation --and heat the inner skin with circulating hot air. Result of the air gap:NIL. One way to overcome is by inserting a Kraft Paper Honeycomb "HoneyCel" into the gap.It will remain there forever-intact. Why 5"-- go for 2" . mm

MR. BRAINWAVE has the right idea. By stopping the direct rays of the sun (radiant heat) you considerably reduce the heat load. Any insulation, up to 2", that you add on top of the roof (under the canopy) would be a plus. I would guess above 2" would not be a good pay back. Be sure it's closed cell and painted with a protective coating to protect it from the elements.

g scott

Sometimes I sits and thinks, then sometimes I just sits.

Adding to other posts, be aware of the additional weight to be withstood by the existing roof by any additional materials, and make sure that

• the exisiting structure can withstand it
• local building codes allow it.

Further to my last post it is important to allow for the "free flow of air", and yes do make sure your existing structure will support the additional weight. Ask about your local building codes. If it is possible you could make the additional roof floating by using external supports. These will be steel posts set in concrete and they will support the beams. It is the air flow that gives the max cooling effect. I suspect at the end money will limit what can be done.

I agree with you: this is the simplest, and cheapest alternative.

This can also be turned into a "high tech roof" by putting sprinklers (or a multiperforated plastic hose) on it: evaporating water will significantly decrease the temperature of the air contained in this chamber, thus producing a marked cooling phenomenon. If water is an issue, try reciculation.

Hellow friend !

At present in the market green netlon net heat absortion net is available in Indian market which mostly use for protection of plant from heat protection.

You procure LESS 25mm opening net and & provide tent on your roof up to 7 feet height of this netlon net.You room temp.will reduced upto 10 °C.

OR

You lay Coconut pads / khuskas-khuskas pads.Provide water sprincal /Arrange cooling pads+500 LT. PVC Tank+Incoming & Oout going reciculation water system.

Commission this system & reduce 10°C temp.

As consultancy my per day charge is Rs.2500+Travelling charge.

My contact no is 9413001929 / 0744-2504940

ONE needs understanding CONDUCTION,CONVECTION,RADIATION.

In India, people copied somebody, who copied somebody ,who copied somebody earlier... and flat solid cast RCC roofs came to stay. All wrong of course.

In 1985 I came settle in Guwahati .

I saw the problem- &solved it. World didn't.I said a few times-but later kept quiet-as I could feel they thought I was all nuts.

People want a flat roof to walk on, have a party in the evening cool , Sleep ON IT whole summers, as you would otherwise boil/sweat WHOLE NIGHT in the sweltering daytime-stored heat Radiating into inside rooms -all night.

And you get what you want-a flat Solid RCC Roof with its massive 4"-5''Thick weight-storing massx Sp. heat. x °C = 500Kgx0.9kJ/(kg.°C)x50°C=2450kJ/m² roof.

Of course YOU do not want THAT.

But Your Leaders,Standards -writers, Technocrats, Research Institutes, Builders know no better and continue to make same suicidal mistake--" Block up all your nation's resources in useless Massive Solid RCC Flat roofs, Thick Brick walls like fortresses of middle ages---and sweat--and deny rest 80% - housing at all!

Must it always be so? NO -if you heed/use simple science.

What AM I talking about?

Just this:

a} Have a flat roof-OK. Solid 5" thick -NO. How thick then? 1" thick with downward ribs carrying rebars to support 15"x8' x1" Precast slabs.To get what?:

• 20% Stored heat which promptly cool down within an hour of sunset.
• Stops solar heat from roof to inside in the long Daylight summer hours (due to non-moving air mass 4" thick due to roofslab ribs looking down )

b}Have identical precast slabs for walls--similar savings/protection-No Burnt Bricks!

c} In multistories same. Calculate the deadweights of 5"RCC Floor slabs vs real loads.

d} Reductions all around-you can now build the house at 20% or less-and get 5 times more comfort and safety from Earthquake jolts.Piled Foundations disappear .

No more for today.

THINK!

A canopy would not help?

A canopy with vents would act as a vented air insulating space and as long as it was structurally sound if a good method. If you are making a canopy that rests 6" above the roof at all points you get even better insulation by filling that space with foam to prevent conduction and radiation. The additiuon of the 6" foam insulation gives you 100 times less heat leakage

Yes --In the present "Fait Accomplii" canopy is THE ANSWER.

Arched Plain Galvanized Steel Sheet canopies to be put on 2m high posts in April start and dismantled/stacked by 4 family members every September end.

Hi, in general terms I agree with you; but you must take into account that this person lives in a house that is ALREADY built... and simply needs to improve it. Consider that he may not be willing or cannot afford building a new house...

We are here to try to help him to solve his problem, not to give him advises he probably may not be able to apply!

It is also true that governments should get involved in this issue by encouraging the design and construction of affordable / comfortable houses using local materials, without forgetting cultural factors and local traditions. Problem is that most goverments are busy doing "something else"... and neglect the citizen!

My reply was for Mukkulmahant. No idea why it appeared here!

We are no satiesfied with your answer for Indian people.If you donot belive with my suggestion.Please be practical & try.

To procure Netlon net less than 25mm net.Provide above 5 feet on plant & observe the temp. above the net & under the net after half & hour.

Main cause :Indian Builder day by day reduce the height of the room. If you see old building you found that height of the indian histrocial building is more in comparision of today building height.Why!

No ventilation provide on side wall of building .In this condition hot air circulate in side the room.

In my view water sprincal system is best method if recirculation of water facilities available at site.

Netlon is also good method for reduce the temp.

Hello,

please, I want some more information, can you please email reply to prasadthupalli@gmail. would like to understand more about your suggestion

Prasad Thupalli

Hello, here is a web site, http://www.insulationsuperstore.com.au/Products/InsulatingPaints/index.php it will give you a good range of options, also a do it your self insulating paint for external use.

Good luck Garth

there is a company in the USA Environmental Protective Coatings that manufactures a product named Thermashield. It is an elastomeric coating that contains ceramic insulative material and can be rolled or brush applied.

www.enviroprotectcoatings.com

Hi there,

take a look at this site

http://www.fao.org/docrep/S1250E/S1250E00.htm#Contents

it has some good advices about insulating roofs under tropical conditions.

Over here temps don't go so up (max 42ºC), and before the coming of modern insulating materials we used to do the following:

1)coat ceiling and walls with white lime wash (renewed every year)

2)inside the house, installing of a second roof made of bamboo poles (about 1-2cm in dia.), about 30-50cm bellow the ceiling

3) In case of planar roof tops, construction of a structure made of bamboo about 2mt high, covered with bamboo poles. This solution is very good, and creates a nice leisure place

Your simplest, lowest cost and best alternative is a "cool roof" coating using a product best suited to the existing surface treatment. There are lots of different products available (see the US EPA's Energy Star web site for more information).

While a silver surface has high reflectivity it also has a low emissivity - whatever you do don't use a shiney silver surface! Touch a white board and a shiny piece of sheet metal (they have approx same reflectance) in full sun to appreciate the difference emissivity makes!

The Greeks have been white-washing their buildings for centuries, but "cool roofs" are just now starting to catch on here in the U.S.

Hello I think you have your self confused here, You remark that white is better at removing heat "emissivity!" this is fine for panel radiators but why do fire fighters use polishes silver suits? Silver will reflect the IR radiation far better than white. It is to prevent the heat energy from getting into the roof not to radiate the heat from inside the hot roof. Gold had the best IR reflectivity but would be slightly expensive. My idea was to add a heat shield that sat above the roof and by being highly reflective prevent the build up of heat in the first place that is why an air gap that allows for a good circulation all round is vital. The only reason that white was has been used is because lime was cheap and easy to apply to walls. It required little or no skill and was widely available. Aluminium paint is better all round. Industrial complexes use it by the barrel load. If white was best they would use it instead. OK enough said.

I believe this is the second thread on cooling Reinforced Concrete roofs in the last few weeks. I believe the best approaches will be based on local weather or climate conditions, such as temperature range between day and night, humidity, seasonal temperature ranges, etc. What works in one area may be very poor in another, even only 50-100 km away.

Nobody has mentioned an idea I learned about when taking a passive solar construction class back in the late 1970's. I believe that in parts of Iran, homes are built with an open masonry thermal chimney in the middle of the home. During the day, the warm air in the room rises up into the chimney where the mass cools it and it falls back down into the room. At the same time, the sunlight is warming the chimney's mass. By the time the heat from the sun has been conducted to the inside, it is evening. As outside air temperatures drop, the chimney is warmer than the room and the outside, so it draws air up and out, bringing cooler outside air into the room. During the night, this air flow continues. The next morning, when the outside temperature rises again, the cycle repeats. No moving parts and no man-made source of energy needed!

It is possible that this type of approach could be used as an addition somewhere in the house in question. However, my concerns in the first paragraph leave this as a potential thought to be evaluated by people who know the local conditions best.

Peace--JMM

there is a company called supertherm who manufacture temprature resistant coatings if it is coated there will no or minimal heat transefer and it keeps the inner rooms cool other way is use ceramic based paint so that the heat transfer is minimal

if it was flat roof brick bat coba of 9 inch thk would have taken care of your problem to greater extent. the other alternative is to use e.p.s boards of 4 inch thickness to be glued to roof and coat the board with polyurethane or polyurea based paints it should reduce heat transfer to greater extent.

one thing we need to remember that it is just not roof which transfer heat thou it is a major contributor so if v insulate roof the result will not be 100%.

protectsystems2004@yahoo.co.in

Insulation is never a hoax. In Pakistan they find it more economical though to only insulate the roof as most of the heat gain in summer is through the roof. I mean look at your fridgerator.. Turn it off and the stuff inside stays cold for a long time thats because its insulated. Insulation keeps heat from entering into our house which means its naturally cooler, your airconditioners dont have to work as much so less electricity bill... you wont need such a huge tonage, IE if you currently use a 1.5 ton ac in a room, with good insulation you could easily downgrade to a 1 ton and save money there too.

Anyway I'm also curious as to the cost as my house has already been constructed but want to insulate now without using utility of the room and I figured foam insulation is the best, but then you have to reseal your roof again with cement or watever so that is costly. Anyone can explain?

roofing contractors

Between 2006( #7) and now We solved it . Cheap and effective.

Top Skyward layer#1 is GalV. Plain Sheet 0.2mm thk - heats up to steady 80 C

Just below are two more layers #2,#3 both Bamboo mats ~@ 4mm thk.

Because of the non moving trapped hot air mass -the Bottom Temp now is at ~ 40C.

Rest is Stefan-Boltzmann radiation rules. PRESTO! Dairy cow sheds love COOLROOF

So do Broilers fatten with less feed.And layers yield larger eggs under COOLROOF.

Up the Frozen hills You lose less thro COOL ROOF in deep winter - thanks to the circuitous path for hot air to bottom ofLayer#1 i.e. steel. We take Orders.